Green Line Extension

The Green Line Extension (sometimes abbreviated as GLX) is an initiative to expand transit services in Greater Boston by extending the Massachusetts Bay Transportation Authority (MBTA) Green Line light rail beyond its current northern terminus at Lechmere Station in Cambridge, Massachusetts. The 4.3-mile (6.9 km) extension is intended in order to improve mobility and regional access for residents in the densely populated municipalities of Somerville and Medford, two cities currently underserved by the MBTA relative to their population densities, commercial importance, and proximity to Boston.

The project would provide Green Line service beyond a relocated Lechmere Station to College Avenue in Medford and to Union Square in Somerville using a two-branch operation, both to be operated within existing MBTA Commuter Rail rights-of-way. The extension is projected to have a total weekday ridership of about 52,000. The Green Line would see an increase in boardings of 30,700, and the MBTA system would see between 7,000 and 8,000 new transit users.

While on the drawing board since 1990, the project has proceeded in fits and starts. Construction finally broke ground on Phase 1 of the Green Line Extension in 2012, with service targeted to begin in 2021. In August 2015, the MBTA disclosed that the project would cost approximately $3 billion, a $1.08 billion increase from previous estimates. The revised cost called into question whether the project could be completed; options like scaling down stations or the maintenance facility will also be considered. In December 2015, the MBTA ended its contracts with the project's general contractor, project manager, and designer, among others, and announced that while components of the project under construction would continue, no further work would be awarded or started; however, in May 2016, a revised version of the project with lower projected construction costs was approved by MassDOT and the MBTA, and new construction will resume if the new plan is approved by the Federal Transit Administration (FTA).

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